The Lebanese prime minister has threatened to resign unless his government agrees to pay Lebanon's share of funding for a UN-backed court investigating the killing of statesman Rafik Hariri.

Prime Minister Najib Mikati came to power in January with the support of the militant group Hezbollah and its political allies, who oppose the Hariri tribunal and want Lebanon to cut all links with the Netherlands-based court.

The court has indicted four Hezbollah members over the 2005 bombing that killed Hariri and 21 other people on the Beirut seafront. Hezbollah, a Shi'ite Muslim movement, has denied any role in the killing.

Mikati has always said his government would honour Lebanon's international commitments.

"I cannot imagine myself as prime minister of Lebanon under my mandate failing to honour its international obligations, or isolated by the international community," Mikati told LBC television late on Thursday.

"With (my) resignation, I would be protecting Lebanon if the funding was not approved," Mikati said, adding that otherwise Lebanon would face international sanctions.

The court has asked Lebanon to pay more than e30 million this year, or 49 percent of its 2011 budget. Mikati's cabinet is expected to discuss the funding next week and may put it to a vote.

Hezbollah, which has said it will oppose the funding, has enough votes with its ministerial allies to block any decision in the 30-seat cabinet.

Mikati said 12 ministers supported funding the tribunal. "We can talk with three or four other ministers. What matters is Lebanon," he said.

The Iranian- and Syrian-backed Hezbollah says the tribunal is politicized and following an Israeli agenda. But it has not ruled out some compromise.

"I will not make a battle out of this... and if someone wants to finance the court from his pocket, that is his affair," Hezbollah Secretary-General Sayyed Hassan Nasrallah said last month. "If it is to be financed from the government treasury.... then the cabinet or parliament will decide."